A train cross a pole in 12 seconds. If the speed of the train is 72 km/h, what is the length of the train? MCQ with Answer and Explanation
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Question #1
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A car travels a distance of 240 km at a uniform speed. If the speed is reduced by 10 km/h, it takes 2 hours longer. Find the original speed.
Correct Answer: Option D
Explanation:
Let original speed be s. 240 / (s - 10) - 240 / s = 2 => 120 / (s - 10) - 120 / s = 1 => 1200 = s(s - 10). Solving s^2 - 10s - 1200 = 0 gives (s - 40)(s + 30) = 0. Since speed is positive, s = 40 km/h.
Let original speed be s. 240 / (s - 10) - 240 / s = 2 => 120 / (s - 10) - 120 / s = 1 => 1200 = s(s - 10). Solving s^2 - 10s - 1200 = 0 gives (s - 40)(s + 30) = 0. Since speed is positive, s = 40 km/h.
This question belongs to:
Maths
Time Speed and Distance
Question #2
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A man covers a distance of 24 km in 3 hours. If he doubles his speed, how much time will he take to cover a distance of 32 km?
Correct Answer: Option D
Explanation:
Original speed = 24 / 3 = 8 km/h. Doubled speed = 16 km/h. Time required for 32 km = 32 / 16 = 2 hours.
Original speed = 24 / 3 = 8 km/h. Doubled speed = 16 km/h. Time required for 32 km = 32 / 16 = 2 hours.
This question belongs to:
Maths
Time Speed and Distance
Question #3
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A person travels a distance of 24 km at a speed of 6 km/h, another 24 km at 8 km/h and a third 24 km at 12 km/h. Find his average speed for the whole journey.
Correct Answer: Option C
Explanation:
Total distance = 24 + 24 + 24 = 72 km. Total time = 24/6 + 24/8 + 24/12 = 4 + 3 + 2 = 9 hours. Average speed = 72 / 9 = 8 km/h.
Total distance = 24 + 24 + 24 = 72 km. Total time = 24/6 + 24/8 + 24/12 = 4 + 3 + 2 = 9 hours. Average speed = 72 / 9 = 8 km/h.
This question belongs to:
Maths
Time Speed and Distance
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